1. Technical Field
The present technology relates to a structure for installing an insert nut in a panel formed with a female screw, and in more detail, relates to a structure for installing an insert nut in a panel member made from a core member with a honeycomb structure and surface plates made from fiber reinforced plastic bonded to two sides of the core member.
2. Related Art
For example, lavatory units that include a toilet and a wash hand basin are installed inside aircraft. These lavatory units are constituted using panel members such as wall panels, floor panels, ceiling panels, door panels, and so on, made from a core member with a honeycomb structure and a first surface plate and a second surface plate made from fiber reinforced plastic bonded to two sides of the core member.
The door and wall panels of the lavatory units are connected with hinges so that the door panel can swivel, and the wall panels are connected together, or wall panels and floor panels or ceiling panels are connected together via angle members.
In this case, the hinges or angle members are fixed to the door or wall panels by screwing a screw or bolt into the female screw of an insert nut embedded in the panel members that form the door or wall panels.
FIGS. 11 and 12 show this type of conventional structure for installing an insert nut in a panel.
As shown in FIGS. 11 and 12, a panel member 10 is made from a core member 12 with a honeycomb structure, and a first and second surface plate 14 and 16 made from fiber reinforced plastic bonded to two sides of the core member 12.
In the structure shown in FIG. 11, an insert nut 18 is embedded in the core member 12 and bonded with adhesive 20 so that one end surface in the axial direction where the female screw 18A is open is coplanar with the first surface plate 14.
Also, in the structure shown in FIG. 12, at a position where the insert nut 18 is embedded in the core member 12, the core member 12 is replaced with a reinforcing member 22 made from urethane foam with high hardness and having greater strength and stiffness than that of the core member 12.
Also, the insert nut 18 is embedded in the reinforcing member 22 and bonded with the adhesive 20 so that one end surface in the axial direction where the female screw 18A is open is coplanar with the first surface plate 14.
Comparing the structure shown in FIG. 11 with the structure shown in FIG. 12, although the pull out strength of the insert nut 18 is equal, the shear strength is superior in the structure shown in FIG. 12 which uses the reinforcing member 22. Here the pull out strength of the insert nut 18 refers to the strength of the installation structure of the insert nut 18 to withstand the action of a force applied to the insert nut 18 embedded in the panel member 10 in the direction normal to the first surface plate 14 in the direction to separate away from the first surface plate 14. Also the shear strength of the insert nut 18 refers to the strength of the installation structure of the insert nut 18 to withstand the action of a force applied to the insert nut 18 embedded in the panel member 10 in a direction along the first surface plate 14.